How to run commandline/terminal utils with Boost.Process 0.5? - c++

Question

I foud out there is a new Boost.Process 0.5 but I cant see how to execute across Windows Linux and Mac ping or echo.
I got it working at leaast on Windows with simple:
#include <string>
#include <iostream>
#include <boost/asio.hpp>
#include <boost/iostreams/device/file_descriptor.hpp>
#include <boost/iostreams/stream.hpp>
#include <boost/process.hpp>
#include <boost/filesystem/path.hpp>
#include <boost/system/error_code.hpp>
namespace bp = boost::process;
namespace bpi = boost::process::initializers;
namespace bio = boost::iostreams;
int main()
{
bp::pipe p = bp::create_pipe();
{
bio::file_descriptor_sink sink(p.sink, bio::close_handle);
boost::filesystem::path p("C:/Windows/System32/cmd.exe");
boost::system::error_code ec;
bp::execute(
bpi::run_exe(p),
bpi::set_cmd_line(L"cmd /c echo --echo-stderr hello"),
bpi::bind_stdout(sink),
bpi::set_on_error(ec)
);
}
bio::file_descriptor_source source(p.source, bio::close_handle);
bio::stream<bio::file_descriptor_source> is(source);
std::string s;
is >> s;
std::cout << s << std::endl;
std::cin.get();
return 0;
}
On windows this works correctly but how to make it crossplatform to work also on Mac and Linux? (I am stupid and do not know how to write one path that would work for any Unix terminal (or at least for Linux Bash and mac default one)) So How to run commandline/terminal utils with Boost.Process 0.5 on Windows and Unix like OSs (better not writing path to terminal each time but just writting app like echo or ping and its arguments)?
...Found related code inside prevoius version:
std::string exe;
std::vector<std::string> args;
#if defined(BOOST_POSIX_API)
exe = "/bin/sh";
args.push_back("sh");
args.push_back("-c");
args.push_back(command);
#elif defined(BOOST_WINDOWS_API)
char sysdir[MAX_PATH];
UINT size = ::GetSystemDirectoryA(sysdir, sizeof(sysdir));
if (!size)
boost::throw_exception(boost::system::system_error(boost::system::error_code(::GetLastError(), boost::system::get_system_category()), "boost::process::launch_shell: GetWindowsDirectory failed"));
BOOST_ASSERT(size < MAX_PATH);
exe = std::string(sysdir) + (sysdir[size - 1] != '\\' ? "\\cmd.exe" : "cmd.exe");
args.push_back("cmd");
args.push_back("/c");
args.push_back(command);
#endif

Answer 1

Under boost.process 0.5 the shell_path() API was introduced so might the following will hook you up
#if defined(BOOST_POSIX_API)
#define SHELL_COMMAND_PREFIX "-c"
#elif defined(BOOST_WINDOWS_API)
#define SHELL_COMMAND_PREFIX "/c"
#endif
filesystem::path shellPath = process::shell_path();
std::string cl = shell_path().string() + " " SHELL_COMMAND_PREFIX " ";
cl += "ping 127.0.0.1";
execute(
set_cmd_line(cl),
throw_on_error()
);
If you really want to hide the #ifdef, I'd go on and edit the boost sources to return also the relevant command prefix (adding new API) , open source after all isn't it ? :).
You could find the relevant sources to edit at boost/process/windows/shell_path.hpp and boost/process/posix/shell_path.hpp